Dynamic TDD Transceiver Isolation Without Series RF Switches
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Solution Overview
Problem
Existing wireless transceivers face challenges in providing sufficient isolation between power amplifier circuits and low-noise amplifier circuits and antennas during time-division duplex operations, especially at high frequencies, leading to degraded signal-to-noise ratio and increased power consumption.
Innovation Solution
A time-division duplex interface circuit dynamically isolates the power amplifier or low-noise amplifier from the antenna based on time-division duplex operations, operating with high impedance to direct signals appropriately between the power amplifier, low-noise amplifier, and antenna, eliminating the need for series switches and supporting multiple power modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a switch is used to selectively connect the transmitter or receiver to the antenna, then transceiver isolation can be provided, but it becomes difficult to achieve sufficient isolation at higher radio frequencies and for some semiconductor manufacturing processes
Solution Approach 1:
The patent extracts the isolation function from a traditional switch component and implements it through impedance transformation circuits that dynamically present high impedance to isolate the inactive path. This removes the need for high-frequency switches that are difficult to manufacture, while achieving the same isolation effect through circuit topology rather than component switching.
Solution Approach 2:
The patent introduces impedance transformation circuits as intermediary elements between the antenna and the transceiver components. These circuits act as mediators that dynamically control signal routing by transforming impedance states, avoiding the need for direct switch connection that causes manufacturing difficulties at high frequencies.
2Reliability
If a switch is used to provide transceiver isolation, then signal routing can be controlled, but signal-to-noise ratio performance degrades and power consumption increases
Solution Approach 1:
The patent extracts the isolation function from the signal path, using impedance transformation to create virtual isolation points that do not physically interrupt the signal flow. This maintains signal integrity and noise figure while achieving the necessary transceiver isolation, unlike switches that directly interrupt and degrade the signal path.
3Reliability
If traditional interface approaches are used, then transceiver isolation can be achieved, but device complexity increases due to the need for series switches along transmitter and receiver signal paths
Solution Approach 1:
The patent merges the isolation function with the existing impedance matching and signal routing circuits. By combining multiple functions (isolation, impedance matching, and signal routing) into unified impedance transformation circuits, the design eliminates the need for separate series switches, thereby reducing overall device complexity while maintaining isolation performance.
4Reliability
If switches are used for transceiver isolation, then signal routing is possible, but manufacturing precision requirements increase for high-frequency operation
Solution Approach 1:
The patent removes the switching function from the design entirely, replacing it with continuous impedance transformation circuits. This extraction of the switching requirement eliminates the need for high-precision high-frequency switches, making the design more tolerant of manufacturing variations and easier to produce at scale.
Data Source
AI summary
An apparatus is disclosed for time-division duplex dynamic transceiver isolation. In an example aspect, the apparatus includes an antenna, a power amplifier circuit including at least one power-amplifying path, a low-noise amplifier, and a time-division duplex interface circuit. The interface includes at least one transmit node coupled to the at least one power-amplifying path, a receive node coupled to the low-noise amplifier, and an antenna node. The antenna node is coupled to the at least one transmit node, the receive node, and the antenna. The interface circuit is configured to connect the at least one transmit node, the receive node, and the antenna node together at both a first time and a second time. The interface circuit is configured to isolate the receive node from the antenna node at the first time and isolate the at least one transmit node from the antenna node at the second time.